In the past, inorganic polymers have been added to various fluids to obtain grease compositions. For example, as disclosed in U.S. Pat. No. 3,332,873, greases are made frm phosphate esters by the addition of certain inorganic polymers which contain double phosphinate bridges and two unidentate ligands. According to U.S. Pat. No. 3,331,774, a diester liquid is converted to a grease by addition of similar inorganic polymers. U.S. Pat. No. 3,331,775 discloses that silicone fluids are converted to greases by adding a relatively low molecular weight doubly bridged chromium phosphinate polymer. And in U.S. Pat. No. 3,522,178, it is revealed that grease compositions can be formulated by using triply bridged chromium atoms where the bridging groups are the anions of phosphinic acids. While the prior art discloses effective thickeners for various fluids, there is a need for polymers that are especially adapted for thickening to a grease-like consistency synthetic fluids containing fluorinated and perfluorinated groups.
It is a principal object of this invention, therefore, to provide fluorinated phosphinic acids which can be reacted with various metal centers to provide thickeners for synthetic fluids containing fluorinated and perfluorinated groups.
Another object of the invention is to provide a process for synthesizing the fluorinated phosphinic acids.
A further object of the invention is to provide polymers that are effective grease thickeners for various high temperature fluids.
Still another object of the invention is to provide grease compositions based on a liquid lubricant thickened with an inorganic polymer obtained by reacting the fluorinated phosphinic acids with various metal centers.
Other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the accompanying disclosure.